Arrangements in accordance with the above are generally designated blood evacuation and blood pressure cuffs and are used, e.g., in operations. Such cuffs are important aids especially in orthopaedics, and hand, nerve, vascular, and plastic surgery. These cuffs are also employed in such applications as support and pressure bandages, e.g., in transporting casualties.
The use of blood evacutation and blood pressure cuffs sometimes results, however, in injuries to blood vessels and nerves due to the mechanical pressure which the cuff exerts on the underlying body tissue. The pressure against the body tissue causes a displacement of tissue from compressed to non-compressed tissue portions, which results in mechanical tissue deformation which is maximal in regions where the pressure gradient is at its greatest. When injuries occur, these are a rule maximal in both musculature and nerve tissues in the immediate vicinity of regions with large pressure gradients. Hitherto known cuffs achieve an uneven distribution of pressure on the body tissue in both the longitudinal direction of the cuff and its circumferential direction, which increases the risk of injuries to the body tissue. In order to reduce the risk of injury, it is thus necessary in use to keep the cuff pressure as low as possible. Especially in the vicinity of the edges of the cuff the pressure differences are large, and thus increase the risk of injury with an uneven pressure distribution in the circumferential direction of the cuff.
A further disadvantage of hitherto known and used cuffs is that in use they strive towards centring the enclosed part of the body in the cuff. This comprises a complication since the enclosed regions have an irregular shape, and a centring may imply undesirable displacements in the enclosed part of the body.
Patent publication No. SE 7400412-8 reveals a blood evacuation cuff which consists of a number of transverse, series-connected, inflatable sections which are disposed on the inside of a stable-shaped cloth which can be shaped into a slightly conical cylinder in that the end regions of the cloth are joined by means of a zip fastener. A successive filling of the sections and thus a corresponding increase in the pressure against the enclosed part of the body can take place by means of valves of a rather complicated structure, connection devices for compressed air, and regulating devices. The valves between the different sections give rise to a certain pressure drop, for which reason the pressure in the last section is considerably lower than in the first in its filled state. For this reason the pressure in the first section must be set to an unnecessarily high value, if the pressure in the last section is to be sufficient. This is a disadvantage. When the cuff is applied to a part of the body with variations in shape and cross-section, local differences in the pressure on the part of the body also occur, since the internal shape of the cuff is defined primarily by the shape of the cloth. In the longitudinal direction of the cuff there runs along the zip fastener (the seam) a zone which lacks inflated sections, and thus the seam causes variations in the pressure on the underlying part of the body. Such an asymmetry with regard to the pressure forces has solely a harmful effect on the part of the body in question.
Patent publication No. SE 7714599-3 reveals a blood evacuation cuff which consists of a number of sections similar to those described above,. In this cuff use is made of a connection tube to each section as well as distribution equipment, which completes the design. This cuff too has the disadvantage of an uneven pressure distribution in application to a part of the body which has a varying shape and cross-section.